This invention relates to biological measurement systems for performing noninvasive inspection of cerebral vasculopathy.
The cerebral vasculopathy (or apoplexy) is a generic term of those diseases which bring nervous symptoms due to organic or functional abnormalities of cerebral blood vessels, and presently it is ranked at the third place of causes of death of Japanese people. About seventy percent of cerebral vascular disturbances is the necrosis (softening or “malacia”) of brain organization occurring due to arterial sclerosis, i.e., ischemia, and involves cerebral thrombosis due to atheromatous hardening of artery in the brain and cerebral embolism due to embolization from outside of the cranium or brainpan. Examples of bleeding include cerebral apoplexy with effusion of blood to inside of brain parenchyma and subarachnoid hemorrhage with bleeding into subarachnoid cavity. Inspection in the acute stage is performed by blood examination, electrocardiogram and X-ray computed tomography (CT), etc. Magnetic resonance imaging (MRI), positron emission tomography (PET), single-photon emission computed tomography (SPECT) or cerebral blood vessel photography is employable as auxiliary inspection therefor.
Regional blood volume changes in a brain are noninvasively measurable by optical topography methodology. The optical topography is a method having the steps of irradiating light onto a body being tested, which light has its wavelength belonging to the visible to infrared range, and detecting by the same photodetector a plurality of light rays of those signals that have passed through inside of the test body to thereby measure a hemoglobin change amount (as disclosed in JP-A-9-019408 or else). Its feature lies in that the restrictiveness against the person under test is kept low when compared to brain function measurement techniques, such as MRI, PET, etc.
However, the cerebral vascular disturbance inspection stated above have a risk of using invasive methods and a penalty of forcing persons under testing in some cases to bear the burden even when a method used is not the invasive one. In addition, it was higher in possibility of overlooking small nidi. Accordingly, it has been difficult to perform the cerebral vascular disturbance examination in a preventive manner. Additionally, with commercially available supersonic wave-based blood vessel hardness inspection apparatus, the brain per se is not observed so that it was impossible to directly estimate arterial sclerosis by direct measurement of the brain. Regarding a phase difference of pulse waves of a plurality of portions also, in the case where a plurality of types of inspection tools are used, system-dependent time delays can occur, thereby making it difficult to measure such phase difference with a required level of accuracy.